With NBC Pact, YouTube Site
Tries to Build a Lasting Business

Over the past decade, large media and tech companies have tried to build mass-market services offering video over the Internet. Someone has finally succeeded big: a startup with 35 employees and an office over a pizza restaurant.

Through YouTube Inc.'s Web service, consumers view short videos more than 70 million times a day, ranging from clips of unicycling jugglers and aspiring musicians to vintage Bugs Bunny cartoons and World Cup soccer highlights recorded from TV. Users post more than 60,000 videos daily, with a limit...